Frankenstein's Cat: Cuddling Up to Biotech's Brave New Beasts (11 page)

For all her optimism, Dresser is also a realist: She knows that cloning alone will not be enough to save a species. The ACRES team isn’t, for instance, tackling the environmental problems that are causing the extinction crisis in the first place, but Dresser believes that reproductive technology is an important piece of the puzzle. As she argues, “There is no one answer to saving endangered species or wildlife on this planet. There are many very good organizations in this world that work on saving habitat. And that’s what they do best. Why not do what
we
do best? My passion burns where I think we can be part of the solution—emphasis on
part
of the solution.”

For her first cloning project, Dresser chose the African wildcat (
Felis silvestris lybica
), a tawny-colored feline with black rings circling its legs and tail. Native to northern and western Africa, the animals are thought to be the ancestors of domestic cats. Dresser decided to duplicate a three-year-old African wildcat named Jazz who already resided at ACRES, and technicians began by taking a tiny sample of the cat’s skin cells. To do the cloning, the researchers planned to employ nuclear transfer—the same technique that researchers had used to create Dolly, CC, and others—but with a twist. Usually, scientists put the DNA of the animal being duplicated into an egg harvested from a female of the same species. When the scientists at A&M cloned Rainbow, for instance, they put her genes into an empty egg taken from another domestic cat.

Nuclear transfer presents extra hurdles for wildlife biologists, who may not be able to get their hands on enough females of an exotic species to provide eggs or act as surrogate mothers. And even if they rounded up a pack of wildcats, they’d be loath to put threatened animals through any unnecessary medical procedures. So when scientists clone endangered animals, they usually use a common, closely related species to serve as egg donors and surrogate mothers. This is known as
interspecies
nuclear transfer.

To clone Jazz, Dresser and her colleagues used everyday housecats. They collected ova from plain ol’ tabbies, removed the nuclei, and then used the standard nuclear transfer procedure to put Jazz’s genes inside. The eggs from the domestic cats now contained instructions for building a wild one.
*
To maximize their chances of success, the researchers implanted the cloned embryos in fifty different lady housecats, and twelve ended up pregnant. The ACRES team carefully monitored the pregnancies, using regular sonograms to check on the developing kittens. Alas, cloning’s inefficiency reared its ugly head, and it was a long and sometimes heartbreaking slog. The first three cats miscarried. One went into premature labor; the kitten did not survive. Several kittens were stillborn. A few more survived their birth, but died within thirty-six hours.

The string of losses was eerily similar to what other cloners had faced, and the incomplete genetic reprogramming associated with nuclear transfer likely contributed to these poor outcomes. But the ACRES team kept at it, and on August 6, 2003, they extracted a tiny wildcat kitten—weighing less than a stick of butter—from the womb of a housecat named Brooke. The vet cleared the male kitten’s nose and mouth and watched him take his first breaths. As soon as Brooke was sewn up, the staff placed the kitten beside her, and the newborn started to nurse. The researchers watched and waited, hoping that when the anesthesia wore off and Brooke came to, she’d bond with the fuzzy ball of foreign DNA pressed up against her.

The odd couple thrived. Brooke took to her maternal duties like a champ, and the little clone continued to suck down her milk. After several uneventful days, Dresser and her colleagues let out a sigh of relief; it looked like the youngster would make it. In a nod to their New Orleans home, they named the kitten Ditteaux (pronounced, in the French fashion, as “Ditto”), and DNA analysis confirmed that he was, indeed, an exact genetic replica of Jazz.

Ditteaux soon had company. That November, Miles and Otis, two more clones of Jazz, were born, as was Caty, a copy of a female African wildcat named Nancy. Spring brought four more Nancy duplicates: Madge, Emily, Evangeline, and Tilly. All the clones were raised by their surrogate mothers, and when they reached sexual maturity, they became swingers, mating in various combinations: Ditteaux and Madge, Ditteaux and Nancy, clone with clone. Their kittens were normal and healthy, and many were eventually sent to live at various zoos.

After these successes, the ACRES researchers moved on to other small exotic cats, cloning the caracal and the Arabian sand cat, the same species that Dresser so proudly showed off when we first met. Next up: lions and the Canadian lynx. They’ve created the cloned embryos already. All that’s left to do is implant them in surrogate mothers. Meanwhile, other labs and researchers have been busy making their own breakthroughs. A European team made a mouflon, a rare breed of wild sheep, using DNA extracted from a female found dead in a pasture, and Korean researchers cloned an endangered cattle species as well as the gray wolf. In 2012, scientists in India ushered Noori, a clone of the rare pashmina goat, into the world.

But that doesn’t mean we’re ready to stock the wild with clones. For every well-earned accomplishment, there are disappointing setbacks; nuclear transfer still produces failures and casualties, whether scientists are duplicating pets, livestock, or wildlife. After making Noah, Advanced Cell Technologies went on to clone the banteng, another variety of endangered cow from Southeast Asia. The first such banteng, born to a domestic cow, was perfectly healthy, but its identical twin, born to a different cow two days later, was hugely oversized at birth. It was a classic case of the “large offspring syndrome” that can plague cloned calves, and the second banteng was euthanized when it was a few days old. If we want to use clones to prop up a population, we’ll need to figure out how to produce healthy animals with less collateral damage and learn more about the long-term health of clones. (Ditteaux is still alive and well at age eight, and as scientists rack up more successes, and more clones come of age, we’ll have the chance to close this knowledge gap.)

*   *   *

If and when we are ready to use clones for large-scale repopulation projects, what would such an endeavor look like? How would we go from a cloned kitten living in a lab to a sustainable wildcat population? In Dresser’s mind, the first task would be simply to create a lot of wildcats. Biologists would collect skin samples from as many of the felines as possible and send them off to a facility like ACRES. The laboratory scientists would turn the skin cells into cloned embryos, and a few months of gestation would turn the embryos into wide-eyed wildcat kittens. But researchers couldn’t just let the clones loose; repopulation projects are major undertakings, requiring long-term scientific, economic, and political commitments. Captive-born wildcats would need to learn survival skills, such as how to hunt on their own, and biologists would need to work with African governments and agencies to secure a safe slice of land for the felines. That wouldn’t be an easy task given that it’s habitat destruction and other forms of human interference that have gotten small exotic cats into trouble in the first place, and the clones might need to start their wild lives on a sanctuary or preserve. After the cats were released, scientists would need to spend years monitoring the animals, analyzing mortalities and documenting how the lab-born cats were adjusting to their new lives. If all went well, the cloned felines would eventually integrate themselves into the wild population and begin to breed.

Many endangered-species reintroductions fail—reviews have turned up success rates that range from 11 to 53 percent—but there have been some important victories. Such programs have boosted the wild populations of black-footed ferrets in the United States, golden lion tamarins in Brazil, and Arabian oryx in Oman, among others.

In addition, animal reintroductions can have ripple effects that help restore the environment itself. Every species is part of a complex ecosystem, and if an animal population suddenly disappears—or its numbers drop precipitously—it can throw the entire system out of whack. For example, some plants rely on animals to disperse their seeds; if these animals die out, the plants are vulnerable, too. When large herbivores disappear, dry shrubs and grasses accumulate, increasing the chance of wildfires. When predators disappear, herds of grazing animals swell, stripping the landscape of vegetation. Some scientists have proposed that by reintroducing animals to their native habitats, we can remodel landscapes and restore healthy ecosystems.

One researcher is putting this idea into action in the northern tundra of Siberia. Today, it’s a desolate place, the snow-covered ground featuring little vegetation beyond shrubs and moss. But it wasn’t always this way. During the Pleistocene epoch, which ended some twelve thousand years ago, the tundra was thick with wild grasses. Woolly mammoths, bison, and wild horses roamed the land. According to Sergey Zimov, the director of Russia’s Northeast Science Station, these large herbivores played a key role in maintaining these grasslands. “In the winter, the animals ate the grasses that grew the previous summer,” Zimov wrote in
Science
. “All the while they fueled plant productivity by fertilizing the soil with their manure, and they trampled down moss and shrubs, preventing these plants from gaining a foothold. It is my contention that the northern grasslands would have remained viable … had the great herds of Pleistocene animals remained in place to maintain the landscape.”

Zimov is trying to turn back the clock by bringing the Pleistocene’s major herbivores—or their modern equivalents—back to the tundra. The animals will be deposited in Pleistocene Park, a large preserve that Zimov established in northern Siberia. Zimov hopes that these large herbivores will help convert the moss-covered landscape back into grassland and restore the diversity of plants and animals that have since disappeared from the region. The project will unfold over the course of decades, but reindeer, moose, musk oxen, bison, and wild horses are already wandering the park and beginning to shape the landscape.

There are more radical proposals, too, such as “rewilding” North America by stocking the Great Plains with wild horses, camels, elephants, cheetahs, and more. (Elephants would serve as stand-ins for mammoths and African cheetahs as proxies for the extinct American cheetah.) According to the scientists championing the idea, these exotic animals will help convert weedy, rat-infested landscapes into lush, biologically diverse grasslands. (And, one imagines, turn a simple trip to Walmart into a drive-by safari.)

The ultimate effects of these ambitious projects are unknown, but even a small-scale reintroduction can help restore an ecosystem. Take the once-abundant gray wolf, which had disappeared from Yellowstone National Park by the mid-1920s. The park’s elk populations exploded in the decades that followed, and these hungry ungulates spent their days chowing down on aspen, willow, and cottonwood trees, stripping branches of their leaves and chewing through saplings.

In 1995 and 1996, officials took a few dozen wolves from Canada and released them into the park. The wolf population slowly grew, and the elk population shrank back to a sustainable level. Today, the vegetation is recovering as well: the trees are taller, and the leaf canopies are thicker. This, in turn, has made the area more hospitable to other species. Songbirds are more abundant, and beavers, which had all but vanished from the park, are returning. What started out as a modest reintroduction project has been restoring Yellowstone to a place where all sorts of species can thrive together.

*   *   *

In the long run, boosting population size is just part of the task for scientists such as Dresser, since many endangered species are also handicapped by a lack of genetic diversity. Consider the enormous variation among human beings, all the different traits possessed by the people in your family, or in your state, or in Mozambique, Sri Lanka, and Iceland. Imagine that a meteor hits Earth and spares (miraculously!) only the people living on your block. Whole family trees, and their unique genetic variants, have been wiped out. You and your neighbors are the only people who can repopulate the planet, and even if you reproduce in every possible combination, your descendants will not be as genetically diverse as the human race was before the meteor.

This reduced diversity creates all sorts of problems. It means a rare and devastating mutation might proliferate. If, purely by chance, the genetic mutation that causes Huntington’s disease is hiding in your neighbor’s genome, your block’s descendants could suffer from the disorder in staggering numbers. And if there are only a few families contributing their DNA to the communal pool, there will inevitably be a lot of inbreeding, which can cause problems of its own. A small gene pool also invites other disasters; if an infectious disease comes roaring along, and everyone’s equally susceptible to it, it could wipe out humanity in one fell swoop.

This is essentially what happens to a species whose numbers have dropped precipitously, such as the cheetah. Evidence suggests that some unknown catastrophe wiped out most of the planet’s cheetahs about ten thousand years ago, leaving just a small number of the cats to pass their genes along. The cheetahs alive today are a remarkably homogeneous bunch, with very little genetic variation. Their low levels of fertility and high rates of sperm abnormalities may be a result of generations of inbreeding.

Cloning, which just makes twins of the creatures that are already out there, won’t solve the genetic-diversity problem for cheetahs or any other species, but we could use the technology to prevent a gene pool from shrinking further. For instance, if scientists learn to clone the cheetah—something they have not yet attempted—they could create carbon copies of the animals that don’t reproduce. If one of the wild felines dies in infancy, and scientists can get their hands on a skin sample, they could clone the youngster, giving it another chance to pass along its genes. They could do the same with cheetahs that reach old age without ever having little ones. In a small population, every genome counts.